Conventional wisdom has long held that some video games are addictive, and recent research establishes that some video games have drug-like effects on the brain. Problem video game use and substance abuse/dependence may develop and influence each other on many levels: Both operate upon and may alter the operation of the brain's reward mechanisms. Heavy use of either may be labeled as a problem behavior. Several popular game types have content that model and normalize substance use. Certain subcultures may encourage heavy use of both video games and substances. Research and practice in health-related fields increasingly acknowledge video game addiction as users seek treatment for it. This project will apply paradigms of risk trajectory and subculture, which have informed research on substance use, to problem video game use. It aims to: (1) establish basic associations among past and present use of video games and substances, separately by video game genre and by type of substance, and find unique predictors of problem use; (2) identify and describe distinct patterns of change, or trajectories, in substance and video game use through childhood, adolescence, and young adulthood, and to explore psychological and socioeconomic risk factors for those trajectories; (3) discover whether, and among whom, video game and substance use contribute to each other through the early life course; and (4), via ethnography, access and develop an in- depth understanding of subcultural contexts for concurrent video game and substance use. The first three aims will be analyzed with data collected from a quota sample of 800 video game users, over half of whom will be current substance users. Quantitative data collection will include careers of use of several distinct video game genres and substances through childhood, adolescence, and early adulthood. Analyses will establish common trajectories of video game and substance risk using general growth mixture modeling, estimate the effect of video game use on substance use, and test possible moderators. The fourth aim will be addressed via ethnographic (qualitative) field work, which will access and gain entrie to subcultures characterized by concurrent use of both substances and video games. Staff will conduct field observations and repeated ethnographic interviews with key informants. Qualitative analyses will employ grounded theory methods to identify structural homologies between affective, ritual, and interactive domains within these subcultures. Findings will contribute to policy and practice by identifying the highest-risk populations for problem video game use, documenting contexts of concurrent use, and determining whether, among which players, and to what extent video gaming is associated with substance use/dependence. PUBLIC HEALTH RELEVANCE: Video gaming is often labeled as addictive and is alleged to contribute to substance use. This project will provide unavailable information about whether and how different genres of video gaming may contribute to substance use/dependence. It will also clearly distinguish the highest-risk subpopulations and locate the most effective points in the life course at which parents and/or public control policies could to intervene to prevent problematic involvements. It could also provide a basis for developing treatments for video gaming addiction and/or possible inclusion in substance abuse treatments.